Nausea

Nausea
A 1681 painting depicting a person vomiting
Specialty	Gastroenterology

Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit.^[1] While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat.^[2]

Over 30 definitions of nausea were proposed in a 2011 book on the topic.^[3]

Nausea is a

Medications taken to prevent and treat nausea and vomiting are called antiemetics. The most commonly prescribed antiemetics in the US are promethazine, metoclopramide, and the newer ondansetron. The word nausea is from Latin nausea, from Greek ναυσία – nausia,^[4] "ναυτία" – nautia, motion sickness, "feeling sick or queasy".^[5]

Causes

Many medications can potentially cause nausea.[8] Some of the most frequently associated include cytotoxic chemotherapy regimens for cancer and other diseases, and general anaesthetic agents. An old cure for migraine, ergotamine, is well known to cause devastating nausea in some patients; a person using it for the first time will be prescribed an antiemetic for relief if needed.^{[citation needed]}

Pregnancy

Nausea or "morning sickness" is common during early pregnancy but may occasionally continue into the second and third trimesters. In the first trimester nearly 80 % of women have some degree of nausea.^[9] Pregnancy should therefore be considered as a possible cause of nausea in any sexually active woman of child-bearing age.^[8] While usually it is mild and self-limiting, severe cases known as hyperemesis gravidarum may require treatment.^[10]

Disequilibrium

A number of conditions involving balance such as

Dysmenorrhea can cause nausea.^[11]

Psychiatric

Nausea may be caused by depression, anxiety disorders and eating disorders.^[12]

Potentially serious

While most causes of nausea are not serious, some serious conditions are associated with nausea. These include

• Gastric outlet obstruction
• Small bowel obstruction
• Colonic obstruction
• Superior mesenteric artery syndrome

Enteric infections

• Viral infection
• Bacterial infection

Inflammatory diseases

• Celiac disease
• Cholecystitis
• Pancreatitis
• Appendicitis
• Hepatitis

Sensorimotor dysfunction

• Gastroparesis
• Intestinal pseudo-obstruction
• Gastroesophageal reflux disease
• Irritable bowel syndrome
• Cyclic vomiting syndrome

Other

• Non-celiac gluten sensitivity
• Biliary colic
• Kidney stone
• Cirrhosis
• Abdominal irradiation^[14]

Outside the abdomen

Cardiopulmonary

• Cardiomyopathy
• Myocardial infarction (heart attack)
• Paroxysmal cough

Inner-ear diseases

• Motion sickness
• Labyrinthitis
• Malignancy

Intracerebral disorders

• Malignancy
• Hemorrhage
• Abscess
• Hydrocephalus
• Meningitis
• Encephalitis
• Rabies

Psychiatric illnesses

• Anorexia and bulimia nervosa
• Depression
• Drug withdrawal

Other

• Post-operative vomiting^[14]
• Nociception
• Altitude sickness

Medications and metabolic disorders

Drugs

• Chemotherapy
• Antibiotics
• Antiarrhythmics
• Digoxin
• Oral hypoglycemic medications
• Oral contraceptives
• Norepinephrine reuptake inhibitors

Endocrine/metabolic disease

• Pregnancy
• Uremia
• Ketoacidosis
• Thyroid and parathyroid disease
• Adrenal insufficiency

Toxins

• Liver failure
• Alcohol

Pathophysiology

Research on nausea and vomiting has relied on using animal models to mimic the anatomy and neuropharmacologic features of the human body.^[15] The physiologic mechanism of nausea is a complex process that has yet to be fully elucidated. There are four general pathways that are activated by specific triggers in the human body that go on to create the sensation of nausea and vomiting.^[16]

• Central nervous system (CNS): Stimuli can affect areas of the CNS including the cerebral cortex and the limbic system. These areas are activated by elevated intracranial pressure, irritation of the meninges (i.e. blood or infection), and extreme emotional triggers such as anxiety. The supratentorial region is also responsible for the sensation of nausea.^[3]
• neurokinin
  receptors (NK1).
• Vestibular system: This system is activated by disturbances to the vestibular apparatus in the inner ear. These include movements that cause motion sickness and dizziness. This pathway is triggered via histamine (H1) receptors and acetylcholine (ACh) receptors.
• Peripheral Pathways: These pathways are triggered via chemoreceptors and mechanoreceptors in the gastrointestinal tract, as well as other organs such as the heart and kidneys. Common activators of these pathways include toxins present in the gastrointestinal lumen and distension of the gastrointestinal lumen from blockage or dysmotility of the bowels. Signals from these pathways travel via multiple neural tracts including the vagus, glossopharyngeal, splanchnic, and sympathetic nerves.

Signals from any of these pathways then travel to the brainstem, activating several structures including the nucleus of the solitary tract, the dorsal motor nucleus of the vagus, and central pattern generator.^[17] These structures go on to signal various downstream effects of nausea and vomiting. The body's motor muscle responses involve halting the muscles of the gastrointestinal tract, and in fact causing reversed propulsion of gastric contents towards the mouth while increasing abdominal muscle contraction. Autonomic effects involve increased salivation and the sensation of feeling faint that often occurs with nausea and vomiting.

Pre-nausea pathophysiology

It has been described that alterations in heart rate can occur as well as the release of vasopressin from the posterior pituitary.^[3]

Diagnosis

Patient history

Taking a thorough patient history may reveal important clues to the cause of nausea and vomiting. If the patient's symptoms have an acute onset, then drugs, toxins, and infections are likely. In contrast, a long-standing history of nausea will point towards a chronic illness as the culprit. The timing of nausea and vomiting after eating food is an important factor to pay attention to. Symptoms that occur within an hour of eating may indicate an obstruction proximal to the small intestine, such as

When a history and physical exam are not enough to determine the cause of nausea and vomiting, certain diagnostic tests may prove useful. A chemistry panel would be useful for electrolyte and metabolic abnormalities.[18] Liver function tests and lipase would identify pancreaticobiliary diseases.^[18] Abdominal X-rays showing air-fluid levels indicate bowel obstruction, while an X-ray showing air-filled bowel loops are more indicative of ileus. More advanced imaging and procedures may be necessary, such as a CT scan, upper endoscopy, colonoscopy, barium enema, or MRI. Abnormal GI motility can be assessed using specific tests like gastric scintigraphy, wireless motility capsules, and small-intestinal manometry.^[14]

Treatment

If dehydration is present due to loss of fluids from severe vomiting, rehydration with oral electrolyte solutions is preferred.^[1] If this is not effective or possible, intravenous rehydration may be required.^[1] Medical care is recommended if: a person cannot keep any liquids down, has symptoms more than 2 days, is weak, has a fever, has stomach pain, vomits more than two times in a day or does not urinate for more than 8 hours.^[19]

Medications

Numerous pharmacologic medications are available for the treatment of nausea. There is no medication that is clearly superior to other medications for all cases of nausea.

Nabilone is also indicated for this purpose.

Alternative medicine

In certain people,

In hospital settings topical anti-nausea gels are not indicated because of lack of research backing their efficacy.[27] Topical gels containing lorazepam, diphenhydramine, and haloperidol are sometimes used for nausea but are not equivalent to more established therapies.^[27]

Ginger has also been shown to be potentially effective in treating several types of nausea.^[28][29]

Prognosis

The outlook depends on the cause. Most people recover within few hours or a day. While short-term nausea and vomiting are generally harmless, they may sometimes indicate a more serious condition. When associated with prolonged vomiting, it may lead to

Nausea and or vomiting is the main complaint in 1.6% of visits to family physicians in Australia.^[6] However, only 25% of people with nausea visit their family physician.^[1] In Australia, nausea, as opposed to vomiting, occurs most frequently in persons aged 15–24 years, and is less common in other age groups.^[6]

See also

• Cancer and nausea
• Vasodilation

References